Barrera threatened to kill him, the teenager testified, if he didn't cover up his father's role by telling his mother he had injured Guadalupe "Lupita" Esquivel himself.

"I was supposed to take the blame and tell my mother I did it" or his father "would do the same thing as" he did to Lupita, Jose testified.

Barrera could face the death penalty in the beating deaths of Lupita and her 5-year-old brother, Ernesto Esquivel. Their bodies were found in March 1998 in shallow graves in Angeles National Forest.

Barrera's wife, Petra Ricardo, also testified Monday as part of a plea bargain. She pleaded no contest to child endangerment last August and is expected to be sentenced to four years in prison.

Ricardo's sister, Maria Ricardo, also is on trial before Los Angeles County Superior Court Judge Ronald S. Coen on charges of child abuse and being an accessory to murder.

Barrera fathered 14 children with his wife and her sister. He lived with Maria Ricardo in a one-room converted garage in Pacoima with their six children and six of Petra Ricardo's eight children, including Lupita and Ernesto.

Petra Ricardo, whom the prosecution also has referred to as Petra Esquivel, testified Monday: "Jose told me, 'I'm sorry, Mama, I was going to drop her on the bed, but I dropped her on the floor.' "

She said she asked each of her children what really happened, suspecting Barrera was to blame.

"I just imagined, I didn't know what he did because I never in my life [had] seen anything like that. . . . She was very, very cold."

Lupita's sister Maria testified last week that her father beat Lupita after she wet her bed, then threw her into a wall with such force that she heard a crack and saw Lupita's head drop. Lupita died of a fractured skull and had bleeding on the brain and other injuries, according to an autopsy.

Petra Ricardo testified that she urged Barrera to help save Lupita's life, but he refused.

"I told Marco we have to take her to the hospital," she testified. "He said, 'We don't have the money for the hospital.' "

Jose testified his father was afraid that Lupita's injuries would arouse suspicion at a hospital.

"She had too many blows on her and [authorities] would ask too many questions," Jose testified. "He was going to blame me to the police."

Ricardo said she went into the mountains one night with Barrera and others to bury Lupita's body.

A few months later, Petra Ricardo said, Barrera went to her home to tell her that another child, Ernesto, also had died. "He said, 'Woman, calm down . . . he had cardiac arrest,' " she testified.

Ernesto's autopsy revealed 13 broken ribs, several fractures of the arms and legs, and multiple bruises, scars, scrapes and ulcers on his body. A 14-year-old stepsister, Luz, testified Monday that Barrera did not like Ernesto. "He thought Ernesto was not his child because he was light [skinned] and his hair was light brown," she said.

Petra Ricardo said she did not witness the beatings of her two children because they lived apart. She said she rarely saw her children after coming to the United States from Mexico in 1997 because Barrera took them from her.